How to Lighten Dark Underarms?

I'm slightly fair-skinned but have very terrible and unsightly dark underarms. Way back in high school, my skin color is even until I started to shave my underarms when hairs started to grow. Its been more 10 years now, that I have this embarrassing problem. Though I already stop shaving back then, still my underarms never return to its original color--fair and smooth. I cant even wear a sleeveless top or even a bathing suit. I cant even ask close friends for fear of humiliation and embarrassment that will scar a lifetime. What are my options for this?